The use of silica/silane filler systems to reduce the rolling resistance and improve the wet traction of passenger car and truck tires is known in the art. A reduction of rolling resistance results in less fuel consumption.
The simultaneous improvement of rolling resistance, wear, and traction, known as expanding the “magic triangle”, requires new approaches to rubber composite development. Precipitated silica has played a major role in the emergence of the green tire, which boasts a large improvement in rolling resistance compared to past technologies. The direct cross-linking of silica (via coupling) into a highly cross-linked polymer matrix, while minimizing interactions between silica particles, is believed to be of vital importance to desirable dynamic mechanical properties of rubber used in the production of passenger car and truck tires. It has been noted that in natural rubber (typically used in the production of truck tires), the proteins present from natural rubber biosynthesis can adsorb preferentially to the silica surface, interfering with the in-situ coupling reaction. Increased dump temperatures, which might improve the coupling efficiency, have also been shown to degrade natural rubber. Thus, there continues to be a need in the rubber industry for improved silica-rubber coupling materials.
Further, it has been found that the incorporation of high surface area filler materials into rubber compositions can cause an undesirable increase in viscosity thereby limiting the amount of high surface area material that can be included in the rubber composition due to process problems. Thus, there is a need to treat such high surface materials (e.g., precipitated silica) with materials which can serve as to render the high surface materials more compatible with the polymeric matrix into which they are being incorporated, improve processing viscosity, and prevent phase separation of the high surface materials from the polymeric matrix.